An Exhaust Gas Recirculation device (or EGR) usually comprises a cooled channel and an uncooled channel connected on the one hand to the inlet circuit of the internal combustion engine and on the other hand to a tapping made in the high pressure zone of the exhaust manifold of the internal combustion engine. The two channels are connected to one another by a valve, called the “by-pass valve”, that regulates the flow of the exhaust gases between the cooled channel and the uncooled channel. Such a recirculation device allows a portion of the exhaust gases to be reutilized in the mixture fed into the internal combustion engine.
From now onwards, the antipollution standards make it necessary to recirculate a larger portion of the exhaust gases. The current architecture has reached its limits with respect to the quantity of exhaust gas that it is possible to recirculate.
To improve the recirculation of the exhaust gases, thought has been given to connecting a recirculation device to the low pressure portion of the exhaust manifold, that is to say downstream of the exhaust gas expansion zone, in order to direct the majority of the exhaust gases toward the internal combustion engine inlet circuit. It is therefore necessary to provide a valve on the low pressure portion of the exhaust manifold making it possible to direct the exhaust gases either toward the outside or toward the recirculation device. However, in this portion of the manifold, the exhaust gases undergo depollution treatments, particularly a post-combustion, that raise their temperature.
The valve must be arranged to withstand this temperature, which increases the cost of the valve and more particularly that of the members controlling the latter such as the actuation motor and the means of transmitting the movement from the motor to the butterfly valve. One solution would be to distance the control members as much as possible from the ducts in which the hot exhaust gases travel. However, it is, on the contrary, desirable for the valve to have a structure that is compact and neatly arranged on the exhaust manifold in order to limit the space requirement. Such a structure promotes a high temperature of the valve and makes it difficult to cool.